Yeah, there is a really good chance that the harness is not plugged in all
the way, or not plugged in at all. If the wires got fetched up while the
radio was being pushed back into the dash, they may have caught and worked
the connector loose, even though it was plugged in when the radio was out of
I would pull it out and check both harnesses. Most of the Ford radios need
a special tool to be removed, but on the most common ones, (4 holes, one in
each corner) you can bend a coat hanger and make your own tool. Simply
insert both tools at the same time, push them all the way in, pull outward
on the tools while pulling out toward you, and the radio should unclip so
you can pull it out.
You didn't mention what year vehicle this is, so the above may not apply as
far as removing the radio. But the older Ford radios were mostly this way.